Just pulled these NGK LFR6A-11 (1-step cold coppers) out after running 4 bottles through this summer. My UPREV map has -4d timing-retard, and low 11's AFR. I run 52N 31F jets @ 100whp shot, ONLY on 100octane (non-oxygenated).

So I am a bit concerned. Attached is pic of CYL#1 (the worst). The other plugs resemble the same but to a lesser degree. I am no pro but I read the following....

1. Ground strap shows coloring down to the threaded base (too much timing?) (need 2-step colder plug?)
2. Porcelain shows brown & black peppering (detonation?)
3. Under 10x magnification, porcelain has slight metallic "diamonds" (detonation upon piston material?)
4. No melt damage to strap or electrode (no pre-iginition?)
5. Base thread has full color, blackened sooty, not oily (rich condition @ idle\cruise)

Engine is VQ35DE with only 27K miles. Plugs were new and used up to 3000 miles.

Any thoughts appreciated.

 

Does look like too much timing/too lean.

Do you have a wideband in the car for the pulls or are you going off of dyno tuned a/f?

 

So the AFR was told to me by my tuner at the time it was mapped. I have an Innovate in-cabin and quick glances while driving never looked questionable. The sensor is in the passenger side (pre-cat). From a dig one time I actually had my wife call out the AFR as I shifted through the RPM range (low\mid 11's, maybe some 12's).

At dyno time, they were monitoring driverside as well as passively via my in-cabin passenger side.

I am most concerned about the peppering. So...is it possible to detonate if supposedly running richer? My guess would be only if there was carbon hot-spots or something. Weird thing is that all the plugs kinda resemble this with CYL#1 & 3 being the worst.

 

Yeah as you say it is weird to see that without a lean condition, maybe could be due to the race gas, I don't have any personal experience running anything other than pump on bottle.

It is always possible to see detonation from timing, regardless of a/f.

 

Yep so I am a sucker for safety. I can get Sunoco 260 GT unleaded 100oct (rebranded as CAM2 GT) at the pump by my house and had the map built around that. I gave the tuner the fuel stats as the stoich is a little lower from the start. In theory, that fuel should be helping me in terms of detonation.

Also having a hard time finding a 2-step copper LFR7A (looks like NGK does not make them). I don't want to go Iridium 2-step cuz of the fine electrode tip I hear can act as a glow plug despite the insulating factor.

 

at least you have something to go by. after 250 miles and 3 bottles my plugs look just as clean as when i put them in. not lean not rich. just perfectly clean. brand new looking

 

This is interesting and now has me thinking....pull to -5d maybe? Right now I am at the general rule 1d/per 25whp, -4d@101whp.

The straps show no initial timing marks and are mostly color burned imho, but I am not experienced at this tea-leaf reading crap...lol

 

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This is helpful as a potential baseline. I intend to keep the sets as I progress through the troubleshooting. I wonder if dropping down to 41N 26F jets for around 75whp, but run on my -4d timing map would color a different result as I would be 1d less than generally recommended for 75whp.

But you run a direct port I thought? meaning your N2O and Fuel are dispersed more accurately into the cylinders as opposed to my single fogger.

 

this has me thinking, CYL #1&3 are farthest from the fogger, might have something to do with why they look worse then the others. agree that it looks like you could pull a degree of timing to be on the safe side, will UpRev do a 1/2 degree?

 

I agree I think 1&3 are overly rich and starved for air. Rich + Not Enough Timing Retard = Detonation in most cases. That is confirmed by the black peppering. one or two spots maybe some fuel burning off, but under 10x mag...they are black carbon bits and not merely staining. Good news for me is that after closer review there is only one small metallic diamond on CYL-1, so I do not think I damaged anything. My tuner seems to agree as well. Ironically, I am in the middle of dropping in an MREV2 with my spacer now as a winter project...so hopefully this will improve as we will pull another degree.

I feel I self-learned a lesson here....IF YOU ARE SPRAYING LEARN TO READ YOUR PLUGS EVERY 3-6k MILES. Doing so by chance may have saved me some expensive grief in the future.

 

Technically, you're supposed to pull the plug right after a WOT pass right after installing them. That way, your plugs don't have other miles on it.

I actually just replaced my plugs and mine look similar, except without the peppering on the porcelain. I got sludge in cyl 1 and 4, though.

 

+1...true that, that is for picky folks trying to actually nitrous tune through plug reads. I guess you are supposed to put new plugs in, take a run, and cut the engine and not idle, then read the plugs. Little overboard for me. I just want to rid the dentonation and loosely monitor.

Found this vid helpful in what to look for and he subscribes to what you are saying as well.

Mods - my apologies in advance if this violates forum rules, but I did not see anything preventing links to public vids.